Adding a shower to a whirpool tub?

Hi guys. I've been searching for a while on how to solve this problem and could use a hand.
About 7 years ago I installed a 6' Jacuzzi tub with a Moen Roman tub faucet on the outside corner (on the drain side of the tub). It's been fine for us, but now it's time to sell the house and people are complaining that there isn't a shower in that bathroom. I'd like to be able to add a simple shower and prefer not to use a hand shower. I dont' think that's what people are looking for. Currently there is only two rows of tile above the tub, but I have enough to make a nice enclosure. (Now my wife gets why I don't throw out good materials!

Would it be ok to tee in before the Roman faucet and then run a "shower only" kit up the wall? I can access the water lines before they go into the faucet, and roughing in the shower piping won't be too tough. I'm not concerned about taking out tile and sheetrock, that part's pretty simple. I just want to make sure what I'm thinking here is ok to do and won't cause problems down the line.
I can supply pictures if that would help.

Tiling on sheetrock around a shower is a disaster waiting to happen. Especially if it doesn't have a vapor barrier behind it. Also, your tub deck may not have a tiling flange, and water on the rim will just get back into the walls. You really want something that won't degrade from the water spray such as a cbu instead of sheetrock. If the tub does have a tiling flange, you could make it work. The tub company (and there are generic ones) may have an add-on tiling flange, if you don't.

So, it could be a real mess, depending on what you're starting with. You have a couple choices on the shower...add a diverter valve or change the tub spout to one with a diverter in it.

You CANNOT just tee into the line and run a shower riser. You MUST pipe from the hot/cold valves TO a diverter fitting, then from that to the tub's spout, and to the shower riser out of the appropriate ports on the diverter. The diverter will typicaly have to drilled into and mounted on the tub rim just like, and near, the Roman tub faucet.